Overspeed prevention

Abstract

A method to prevent overspeed of an internal combustion and attached ancillary devices in a mechanized vehicle includes one or more procedures to prevent improper gear selection to disengage the lockup function of a torque converter, to initiate engine braking and to destroke variable displacement hydraulic pumps. Requested gear selection in downshift is allowed only after interrogation of brake pressure, ground speed, shift selection requested and torque converter output speed. The torque converter lock-up solenoid is activated or deactivated in response to torque converter output speed which is compared to selected values to engage or disengage. Engine braking using a compression release braking system response to engine RPM in manual or automatic mode to prevent overspeed. Variable displacement pumps are destroked in response to engine RPM by adjusting swashplate control. The systems may be operated independently or under the control of a common electronic module.

What is claimed is:  
     
       1. A method to prevent overspeed of an engine of a work machine having a ground-engaging device and a transmission connecting the ground-engaging device to the engine, the method comprising: 
       producing an operator transmission command signal responsive to at least one of an operator transmission command and an automatic transmission command;  
       producing a ground speed signal responsive to a ground speed of the work machine;  
       producing a transmission output speed signal responsive to an output speed of the transmission;  
       producing a brake status signal;  
       producing an engine speed signal responsive to an operating speed of the engine;  
       receiving the operator transmission command signal, the ground speed signal, the transmission output speed signal, the brake status signal, and the engine speed signal; and  
       producing a transmission control signal responsive to the transmission output speed signal and at least one of the operator transmission command signal, the ground speed signal, the brake status signal, and the engine speed signal.  
     
     
       2. The method of  claim 1 , wherein the brake status signal is produced responsive to at least one of a brake accumulator pressure and a compression release braking system status. 
     
     
       3. The method of  claim 1 , including: 
       allowing the operator transmission command to be carried out responsive to the transmission control signal.  
     
     
       4. The method of  claim 1 , including: 
       denying the operator transmission command responsive to the transmission control signal.  
     
     
       5. The method of  claim 4 , including: 
       notifying an operator that the operator transmission command is denied.  
     
     
       6. The method of  claim 4 , including: 
       repeating the method;  
       monitoring the transmission control signal as the method is repeated at least once; and  
       allowing the operator transmission command responsive to the transmission control signal.  
     
     
       7. The method of  claim 1 , including: 
       providing an exception range;  
       receiving the transmission control signal and producing a transmission allowed signal responsive to the transmission control signal falling within the exception range; and  
       allowing the operator transmission command responsive to the transmission allowed signal.  
     
     
       8. The method of  claim 1 , including: 
       providing a compression release engine braking system;  
       controlling actuation of the compression release engine braking system responsive to the transmission control signal.  
     
     
       9. The method of  claim 1 , including: 
       providing a variable capacity hydraulic pump associated with the engine;  
       destroking the variable capacity hydraulic pump responsive to the transmission control signal.  
     
     
       10. The method of  claim 1 , including: 
       recording at least one of the transmission control signal, the operator transmission command signal, the ground speed signal, the transmission output speed signal, the brake status signal, and the engine speed signal in an overspeed log.  
     
     
       11. The method of  claim 1 , including: 
       providing a torque converter;  
       producing a torque converter output speed signal responsive to an output speed of the torque converter;  
       receiving the operator transmission command signal, the torque converter output speed signal, the ground speed signal, the transmission output speed signal, the brake status signal, and the engine speed signal; and  
       producing a transmission control signal responsive to at least two of the operator transmission command signal, the torque converter output speed signal, the ground speed signal, the transmission output speed signal, the brake status signal, and the engine speed signal.  
     
     
       12. The method of  claim 11 , including: 
       providing a lockup clutch associated with the torque converter; and  
       controlling actuation of the lockup clutch responsive to the transmission control signal.  
     
     
       13. A work machine, comprising: 
       at least one ground-engaging device adapted to provide motive power to the work machine;  
       an engine;  
       a transmission adapted to link the ground-engaging device and the engine; and  
       an overspeed prevention system including:  
       an operator transmission control device adapted to provide an operator transmission command;  
       a ground speed sensor adapted to produce a ground speed signal responsive to a ground speed of the work machine;  
       a transmission output sensor adapted to produce a transmission output speed signal responsive to an output speed of the transmission;  
       a brake sensor adapted to produce a brake signal responsive to at least one of a brake accumulator pressure and a compression release braking system status;  
       an engine speed sensor adapted to produce an engine speed signal responsive to an operating speed of the engine; and  
       an electronic control module adapted to receive at least two of the operator transmission command signal, the ground speed signal, the transmission output speed signal, the brake status signal, and the engine speed signal, and responsively produce a transmission control signal.  
     
     
       14. The work machine of  claim 13 , wherein the transmission control signal allows the operator transmission command to be carried out. 
     
     
       15. The work machine of  claim 13 , wherein the transmission control signal denies the operator transmission command. 
     
     
       16. The work machine of  claim 15 , wherein a transmission denial warning device is activated responsive to the denial of the operator transmission command and communicates to an operator that the operator transmission command has been denied. 
     
     
       17. The work machine of  claim 15 , wherein the transmission control signal is produced again and the operator transmission command is automatically carried out responsive to an acceptable transmission control signal. 
     
     
       18. The work machine of  claim 12 , including a compression release engine braking system associated with the engine and wherein an actuation of the compression release engine braking system is controlled responsive to the transmission control signal. 
     
     
       19. The work machine of  claim 13 , including a torque converter associated with the transmission and a lockup clutch associated with the torque converter, wherein a torque converter output speed sensor produces a torque converter output speed signal responsive to an output speed of the torque converter, the electronic control module receives at least two of the operator transmission command signal, the torque converter output speed signal, the ground speed signal, the transmission output speed signal, the brake status signal, and the engine speed signal and responsively produces the transmission control signal, and an actuation of the lockup clutch is controlled responsive to the transmission control signal. 
     
     
       20. The work machine of  claim 13 , including a variable capacity hydraulic pump associated with the engine, wherein the variable capacity hydraulic pump is destroked responsive to the transmission control signal. 
     
     
       21. A method to prevent overspeed of an engine of a work machine having a ground-engaging device, a brake system, and a transmission connecting the ground-engaging device to the engine, the method comprising: 
       producing an operator transmission command signal responsive to at least one of an operator transmission command and an automatic transmission command;  
       producing a ground speed signal responsive to a ground speed of the work machine;  
       producing a transmission output speed signal responsive to an output speed of the transmission;  
       producing a brake status signal responsive to a hydraulic pressure of the brake system;  
       producing an engine speed signal responsive to an operating speed of the engine;  
       receiving the operator transmission command signal, the ground speed signal, the transmission output speed signal, the brake status signal, and the engine speed signal; and  
       producing a transmission control signal responsive to at least two of the operator transmission command signal, the ground speed signal, the transmission output speed signal, the brake status signal, and the engine speed signal.